Immunogenecity and immunoprotection of recombinant Hantaan virus nucleocapsid protrein(NP)expressed in E.coli were studied.First,mice were immunized with the recombinant NP,the titer of antibody against Hantaan virus was determineted using indirect immunofluorescenceassay,it was1:12800 in 4 weeks after immunized.Then,the spleen cells and sera of immunizedmice were transferred to 3￣4 day-old mice in 24 hours after the mice infected with lethal dose ofHantaan virus.The protection rates of spleen cells were 10～38%,but the sera could not protectmice from death,at the same time, it also did not change the living time of mice with lethal Han-taan virus infection. The results indicate that NP ean induce the cell-mediated immune protectionbut cannot induce the antibody-mediated immune protection and the early death in Hantaan virusinfection mice.